Post on 14-Mar-2018
Mohammed AlfarsiBDS, MDSc(Pros), PhD
www.DrMohdAlfarsi.comwww.محمدالفارسي.com
Mohd@DrMohdAlfarsi.com@DrMohdAlfarsiDrMohdAlfarsi056 224 2227
Introduction to Impressions for FPDs
Friday, 7 March 14
Why Do We Take Impressions?Overview
Friday, 7 March 14
Why Do We Take Impressions?Overview
Requirements:- Should be biocompatible.- Should be cost-effective.- Be fluidly enough to adapt to the oral tissues- Be viscous enough to be contained in the impression tray.- Set in reasonable time.- Should not be distorted when removed after setting.- Should remain dimensionally stable until poured.- Should reproduce surface details.
Friday, 7 March 14
Types of ImpressionsIntroduction
Friday, 7 March 14
Types of ImpressionsIntroduction
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Impression compound
(green sticks)
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Impression compound
(green sticks)
Reversible hydrocolloid
(agar)
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Impression compound
(green sticks)
Reversible hydrocolloid
(agar)
Irreversible hydrocolloid
(alginate)
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Impression compound
(green sticks)
Reversible hydrocolloid
(agar)
Irreversible hydrocolloid
(alginate)
Elastomeric impression
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Impression compound
(green sticks)
Reversible hydrocolloid
(agar)
Irreversible hydrocolloid
(alginate)
Elastomeric impression
Polysulfide
Silicone
Polyether
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Impression compound
(green sticks)
Reversible hydrocolloid
(agar)
Irreversible hydrocolloid
(alginate)
Elastomeric impression
Polysulfide
Silicone
Polyether
Condensation silicone
Addition silicone
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Impression compound
(green sticks)
Reversible hydrocolloid
(agar)
Irreversible hydrocolloid
(alginate)
Elastomeric impression
Zinc oxide-eugenol impression
Polysulfide
Silicone
Polyether
Condensation silicone
Addition silicone
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Impression compound
(green sticks)
Reversible hydrocolloid
(agar)
Irreversible hydrocolloid
(alginate)
Elastomeric impression
Zinc oxide-eugenol impression
Impression plaster
Polysulfide
Silicone
Polyether
Condensation silicone
Addition silicone
Friday, 7 March 14
Types of ImpressionsIntroduction
Reversible Irreversible
Impression compound
(green sticks)
Reversible hydrocolloid
(agar)
Irreversible hydrocolloid
(alginate)
Elastomeric impression
Zinc oxide-eugenol impression
Impression plaster
Polysulfide
Silicone
Polyether
Condensation silicone
Addition silicone
Friday, 7 March 14
Impression materials
Friday, 7 March 14
AlginateImpression materials
- Inexpensive- Easy to manipulate- Requires simple equipment- Hydrophilic- Comfortable for the patient
Friday, 7 March 14
AlginateImpression materials
- Inexpensive- Easy to manipulate- Requires simple equipment- Hydrophilic- Comfortable for the patient
- Can not reproduce fine details- Mixing time can affect the strength- Water temp. can affect setting time- Must be poured within an hour- Second pour is not as accurate- Sudden removal is required
Friday, 7 March 14
Impression materials
Friday, 7 March 14
Addition SiliconeImpression materials
- Accurate reproduction of surface details.- Does not require immediate pour.- Can be poured more than once, most accurate is first one.- Easy pouring, if hydrophilic surfactant is incorporated.- Stays dimesionally stable for long time.
Friday, 7 March 14
Addition SiliconeImpression materials
- Accurate reproduction of surface details.- Does not require immediate pour.- Can be poured more than once, most accurate is first one.- Easy pouring, if hydrophilic surfactant is incorporated.- Stays dimesionally stable for long time.
- Relatively expensive.- Releases hydrogen gas. But recent materials do not.- Hydrophobic. But recent material are hydrophilic- Latex gloves inhibit the setting.- Can be technique sensitive.
Friday, 7 March 14
Impression materials
Friday, 7 March 14
PolyetherImpression materials
- First elastomer developed to be impression material.- Hydrophilic.- Very accurate reproduction of surface details.- Dimensionally stable.- Can be poured more than once.
Friday, 7 March 14
PolyetherImpression materials
- First elastomer developed to be impression material.- Hydrophilic.- Very accurate reproduction of surface details.- Dimensionally stable.- Can be poured more than once.
- Expensive.- Stiff, should not be used if there are undercuts.
Friday, 7 March 14
Impression materials
Friday, 7 March 14
ViscositiesImpression materials
- Light.- Medium.- Heavy.- Extra heavy (Putty).
Friday, 7 March 14
ViscositiesImpression materials
- Light.- Medium.- Heavy.- Extra heavy (Putty).
Shear-thinning(pseudo-plasticity)
Friday, 7 March 14
Impression techniques
Friday, 7 March 14
How to Take an Impression for a FPD?Impression techniques
Friday, 7 March 14
Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
What can go wrong?Troubleshooting
Friday, 7 March 14
The End
Friday, 7 March 14
The End
References
Friday, 7 March 14